A) Field of the Invention
The invention relates to a device for gas rinsing a hollow guide for CO.sub.2 lasers, the hollow guide being designed as a thin ceramic hollow tube which is guided within an outer tube, preferably made from stainless steel, while leaving a hollow space between the latter and the hollow ceramic tube, and the outer tube being provided on the proximal side with a connecting part having a gas connection and a part for receiving a focusing optical system.
B) Description of the Prior Art
Lasers are frequently used in medicine for diagnosis and therapy or for surgical purposes. In recent years the CO.sub.2 laser has thus been successful, in particular in gynecology, and is used in this field particularly in laparoscopy, to remove, for example, growths on the uterus or on the ovaries. A particular advantage of this method is in the ability to work largely in a blood-free manner, as small blood vessels are immediately coagulated due to the thermal effect of the laser beam. More recently so-called hollow guides are used as applicators for CO.sub.2 laser therapy, which are introduced by means of a trocar sleeve, for example into the abdominal cavity of a female patient. Hollow guides of this type consist of a thin hollow ceramic tube, which is encased in a stainless steel tube for reasons of stability, and a coupling component containing a convex lens made from zinc selenide. The lens serves to focus the laser beam on the inlet orifice of the hollow ceramic tube.
One problem in using such hollow guides results from the fact that they may become very hot, especially when using a high performance laser, and when used for a long period of therapy. This heating poses a danger; this is a danger to the user and the patient and may also lead to destruction of the hollow guide. Heating of the hollow guide is caused by the multiple reflections resulting from the geometry of the beam and absorptions associated with them on the wall of the hollow tube. Furthermore, steam and burnt gas produced when the laser is directed at body fluid and during coagulation and cutting with the laser beam, may penetrate the distal region of the ceramic hollow tube. These impurities absorb the laser energy particularly strongly and may thus lead to very high heating of the hollow guide and hence cause an immediate danger for the patient.
Hollow guides must therefore be intensively cooled and kept free of impurities to ensure their safe and effective use. For this purpose hollow guides are conventionally connected to CO.sub.2 gas rinsing systems having adjustable flow rates, by means of a rinsing gas connection, such as may be seen for example from the instructions for use for a hollow guide for a CO.sub.2 laser transmission system from Messrs. Heraeus. Differing flow rates are required for the protection from, or for the removal of, impurities, depending on the diameter of the hollow guide.
Rinsing impurities away from the hollow tube is known, for example from German utility model 7810089. Furthermore, German utility model 1810089 and German utility model 7709964 also describe advantageous possibilities for rinsing the distal connecting element when using a laser in conjunction with a lens system or a laser fiber. In this process, the distal connecting element is rinsed by introducing the gas stream to the distal end of the guide tube past the guide tube which receives the lens system or the laser fiber. The guide tube is surrounded by an outer tube for this purpose and the distal end of the outer tube may be rolled in to divert or direct the gas stream to the distal connecting element.
Impurities, at the distal connecting element of hollow guides having optical systems, or impurities in the interior of hollow tubes can be avoided or removed in this manner. The hollow tubes are also cooled in this manner.
However, the disadvantage of using the hollow guides according to the state of the art is that steam and smoke produced in a body cavity, and impairing the view of the user when working with the laser, cannot be adequately removed from the area of application using the gas flow rates which can be achieved using hollow guides according to the state of the art. Therefore additional gas rinsing devices, which can be introduced into the body cavity by means of an additional incision, are always required when using a hollow guide in body cavities in order to be able to provide a good view for the operator.